We have described the three-dimensional shape of cells and of intercellular flow channels in three rapidly transporting epithelia and have derived a simple mathematical relationship between the structural and functional parameters in those epithelia. With such an analytic formulation the electron microscopic picture of an epithelium may become, in effect, a "fingerprint" of its function. In proposed work we examine the structure and function of a wide variety of different epithelia from different species to test the validity and wider application of our structure-function correlation model and the hypothesis of cell deformability upon which it is based.